Neither Wind nor Rain...

Taking lessons learned from 2018's Hurricane Michael, the Federal Emergency Management Agency (FEMA) has issued a pair of advisories outlining best practices for helping construct and retrofit buildings to withstand the ravages of such a storm: wind and water.  The first includes the following (quoted from the document itself):

Even when a retrofitted element performs as intended, the building as a whole may not achieve the target performance level intended by the retrofit. To achieve the intended performance level, all building elements that may be vulnerable to wind damage should be identified, and a comprehensive plan for executing the needed retrofits should be developed. The five-step process outlined [in this FEMA document] is an approach for consideration.

Five Steps (from FEMA document cited above)

 Step 1: Perform a Comprehensive Wind Vulnerability Assessment....To understand a building’s wind resistance, it is important to have a vulnerability assessment performed. A thorough wind vulnerability assessment is intended to identify all significant wind and wind-driven rain vulnerabilities (i.e., those vulnerabilities that could adversely affect building operations)....

Step 2: Evaluate Options for Repairs, Retrofits, and New Construction....  In the case of damaged buildings, there are four options to achieving acceptable risk levels: 

1.  Repair the damage and perform the minimum amount of work necessary to comply with the building code....

2.  Repair the damage and perform additional wind retrofit work that is beyond that required by the building code to address identified wind vulnerabilities.

3.  Design and construct a new facility.

4.  Move operations to another facility capable of meeting the given needs.

Step 3: Consider Incremental versus Full Retrofit.  If the Step 2 evaluation results in the decision to perform a wind retrofit, but funds are insufficient to mitigate all significant vulnerabilities, the best approach is to prioritize mitigation actions per the recommendations of the assessment team.

Step 4: Implement Wind Retrofit Best Practices.  After determining the scope of the planned retrofit (Step 3), the next step is to perform the retrofit design work and prepare contract drawings and specifications.

Step 5: Plan for Unexpected Failures.  The true vulnerability of a building may not be known until tested by an actual wind event. Field testing and the various field checks conducted during a vulnerability assessment are performed at discrete locations, so data on conditions and wind and water resistance are only obtained for the areas that are tested or checked. There is always the potential for an undetected anomaly that could allow wind damage or wind-driven rain infiltration. A best practice is to develop contingency plans for interruption of facility operations in case wind damage or leakage occurs.

The second advisory addresses roof coverings, underlayment, vents, exterior wall coverings, soffits, glazed openings, doors, and all related construction practices to harden structural envelopes against hurricane damage.  Both are highly recommended.